Cement mortars that are prepared by adding a water reducing agent to cement have been and being popularly used for civil engineering and building construction works. Furthermore, a calcium sulfoaluminate based or lime type expansive additive and a foaming agent of aluminum powder are added to cement to make it non-shrinkage and then river sand and/or silica sand is compounded to produce paste or mortar. Materials prepared in this way are being popularly employed in construction works particularly to fill fine gaps of concrete structures and gaps produced by back-action construction method, to repair and reinforce structures and also to fill spaces under base plates of machines and apparatus and under slabs of tracks.
Generally, filling mortar materials that are used in civil engineering and building construction works are also referred to as grouts. Grouts include PC grouts, grouts for pre-packed concretes, back filling grouts for tunnels and shields, grouts for pre-casting, grouts for repairing and reinforcing structures, grouts for reinforcing joints, grouts for under bearings of bridges, grouts for under slabs of pavements and tracks, and grouts for under storage containers of nuclear power generation plants.
The quality of concrete to be used for civil engineering and building structures has been improved in recent years and accordingly mortar materials to be used as grouts are required to show a high strength, a high fluidity and a low shrinkage (see Non-Patent Document 1).    Non-Patent Document 1: “An Experimental Study on Filling Performances of High Strength Grout Materials”, Summary of the Academic Lectures in the General Convention of Japan Society of Architects, No. 1313, August 1995.
Particularly, there is a demand for cement mortars to be used for filling reinforcing joints connecting reinforcements of structures of reinforced concrete or pre-cast concrete that manifests a high strength and a low shrinkage in addition to a high fluidity because of the current availability of high strength concrete for large and improved earthquake proof reinforced concrete structures that requires by turns joints showing an enhanced strength and a high resistance.
On the other hand, it is known that the use of a cement based grout composition combined with a specific water reducing agent can provide an effect of low temperature dependency, a remarkable effect of retention of fluidity and filling ability and an effect of improving the strength for a long period of time (see Patent Document 1)    Patent Document 1: JP-A-2003-171162
Patent Document 1 describes an invention of “a cement based grout composition of cement, fine aggregate, a water reducing agent, an expansive additive, inorganic finer powder and a foaming substance, characterized in that the compounding ratio of the water reducing agent is 0.05 to 4 mass portions relative to 100 mass portions of cement and the water reducing agent contains in 100 mass portions thereof a melamine sulfonic acid based water reducing agent, a naphthalene sulfonate based water reducing agent and a lignin sulfonic acid based water reducing agent respectively by 0.05 to 4 mass portions, by 10 to 30 mass portions, 55 to 85 mass portions and 5 to 20 mass portions” (claim 1) as well as a cement based grout composition according to claim 1 or 2, characterized in that the inorganic fine powder is fly ash showing a Blaine's specific surface area of not less than 4,000 cm2/g and an ignition loss of not more than 3.5% (claim 3) but it does not suggest the use of any siliceous fine powder whose silicon dioxide content ratio and hydrogen ion concentration are found within specific respective ranges. Additionally, while it describes the use of a calcium aluminoferrite based expansive additive showing a Blaine's specific surface area of 4,000 cm2/g (observed by a method conforming to JIS R 5201) (paragraph [0028]), it does not describe the use of a polycarboxylic acid based water reducing agent nor suggest the use of a combination of a specific siliceous fine powder, a calcium aluminoferrite based expansive additive and a polycarboxylic acid based water reducing agent in order to a filling material for a reinforcing joint showing an excellent retention of fluidity, a high strength and a low shrinkage.
Furthermore, a method of manufacturing mortar-concrete showing a high strength by using specific aggregate and silica fume in combination (see Patent Document 2).    Patent Document 2: JP-A-05-58701
While Patent Document 2 describes an invention of a “method of manufacturing mortar-concrete characterized by using aggregate containing quartz or feldspar and having physical properties including a specific gravity of not less than 2.58, a shear hardness of not less than 90 and a compressive strength of not less than 2,000 kgf/cm2, and water-binder ratio by not more than 25%, adding silica fume containing SiO2 by not less than 90% as admixture by 5 to 20% of the weight of the cement and preparing them by using a high performance AE water reducing agent” (claim 1). However, while it describes silica fume only in terms of SiO2 content ratio (paragraphs [0006], [0007] and [0009]), it does not describe hydrogen ion concentration nor shows it any intention of improving the fluidity. Furthermore, while it describes the use of a high performance AE water reducing agent, it does not describe anything about using an expansive additive in combination nor about manufacturing a filling material for a reinforcing joint showing properties including an excellent retention of fluidity, a high strength and a low shrinkage prepared by adding silica fume, a calcium aluminoferrite based expansive additive and a polycarboxylic acid based water reducing agent in combination.
It is also known that a cement composition of belite-rich cement, silica fume, a cement dispersant containing a polycarboxylic acid based polymeric compound having a polyalkylene glycol chain as principal ingredient, a lime based additive or an organic shrinkage reducing agent, a substance for generating pressure countering the shrinkage stress produced by the hydration reaction of the belite-rich cement and fine aggregate having a specific gravity of not less than 3.4 and a coefficient of water absorption between 0.5 and 1.5% provides a good retention of fluidity and a high strength (see Patent Document 3).    Patent Document 3: JP-A-2003-286064
Patent Document 3 describes “containing belite-rich cement as indispensable ingredient” (paragraph [0014]) and also that a composition prepared without using belite-rich cement (by using ordinary cement) showed a flow value less than 140 mm and 60 minutes after mixing and did not stably provide a high fluidity in a physical property evaluation test where a cement compound containing silica fume, a cement dispersant containing a polycarboxylic acid based polymeric compound having a polyalkylene glycol chain as principal ingredient, a lime based additive, a substance (carbon based foaming agent) for generating pressure countering the shrinkage stress produced by the hydrating reaction of the belite-rich cement and fine aggregate having a specific gravity of not less than 3.4 and a coefficient of water absorption between 0.5 and 1.5% is mixed with water added to a predetermined ratio (paragraphs [0049], [0051] and [0054]). Thus, it suggests that it is not possible to provide a cement composition having a good fluidity, a high compressive strength and a good non-shrinkage without using belite-rich cement. While the above document describes the average grain size and the carbon content of the silica fume used there (paragraph [0038]), it does not describe anything about the hydrogen ion concentration. Furthermore, it describes that a lime based expansive additive is combined with silica fume and polycarboxylic acid based water reducing agent for use (paragraph [0018]) but does not described about obtaining a filling material showing an excellent retention of fluidity, a high strength and a low shrinkage for a reinforcing joint by using silica fume, calcium aluminoferrite based expansive additive and a polycarboxylic acid based water reducing agent in combination.
It is known to use powder of fine particles containing silicon dioxide (SiO2) as principal ingredient and also zirconium dioxide as an ingredient in order to manufacturing mortar-concrete that can be handled with ease during the manufacturing process and shows a high strength and a high workability by using a water reducing agent to a small extent (see Patent Document 4).    Patent Document 4: JP-A-2004-203733
Patent Document 4 describes an invention of “a method of manufacturing mortar-concrete characterized in that it is prepared by using a mixture obtained by mixing cement, fine aggregate and powder of fine particles containing silicon dioxide (SiO2) as principal ingredient and also zirconium dioxide as an ingredient” (claim 2) and the use of “SiO2: 92.74 wt %, ZrO2: 4.76 wt %, Fe2O3: 0.35 wt %, A2lO3: 0.01 wt %, TiO2: 0.05 wt %, H2O: 0.18 wt %, Na2O: 0.02 wt %, pH: 4.2 and specific surface area: 9.22 m2/g as observed by the BET method”, “density: 2.45 g/cm3, SiO2: 94.5 wt %, ZiO2: 4.0 wt %, pH: 3 to 4, average particle size: 1 μm and specific surface area: 8.7 m2/g as observed by the BET method (paragraphs [0025] and [0055]) as fine particles (special siliceous fine powder), and a polycarboxylic acid based water reducing agent (paragraph [0054]). However, as it describes that “in the method of manufacturing concrete of this embodiment, the additive of special siliceous fine particles scatters less because they have a large particle size if compared with conventional additives using silica fume of a small particle size so that it is possible to secure a correct mixing ratio and facilitate the operation (paragraph [0038]), it only says that the particle size of the siliceous fine powder is important and does not disclose any technological idea of using “siliceous fine powder having a silicon dioxide (SiO2) content ratio of not less than 90% and a hydrogen ion concentration found in an acid region” in order to obtain a filling material for a reinforcing joint showing an excellent retention of fluidity, a high strength and a low shrinkage. Additionally, the invention described in Patent Document 4 avoids the use of an expansive additive (paragraph [0006]) and therefore those skilled in the art cannot easily get to the idea of using special siliceous fine powder and a calcium aluminoferrite based expansive additive in combination on the bases of the above invention.
An invention of obtaining heavy weight mortar prepared by compounding heavy weight aggregate that shows a suppressed temperature rise without segregation of ingredients is also known (see Patent Document 5)    Patent Document 5: JP-A-2005-47772
Patent Document 5 describes “a mortar composition prepared by compounding cement, an expansive additive, a binder containing pozzolana fine powder, fine aggregate and a water reducing agent, characterized in that the fine aggregate contains particles with a particle size not greater than 0.15 mm by 10 to 20% and has a specific gravity of not less than 3.0 and a particle size of not greater than 2.5 mm, the content thereof being 200 to 300 portions relative to 100 portions of the binder” (claim 1). It also describes that silica fume is used as pozzolana fine powder (paragraph [0020]), and polycarboxylic acid based water reducing agent is used (paragraph [0025]). However, while it shows a calcium sulfoaluminate based expansive additive (paragraph [0011]), it does not describe anything about a calcium aluminoferrite based expansive additive nor describes it about the silicon dioxide content ratio and the hydrogen ion concentration of silica fume. Thus, it is not intended to dissolve the problem of obtaining a filling material for a reinforcing joint showing an excellent retention of fluidity, a high strength and a low shrinkage by using a calcium aluminoferrite based expansive additive, a special pozzolana fine powder and a polycarboxylic acid based water reducing agent in combination.
An invention of mortar that shows a high fluidity if the water-cement ratio is low and a high compressive strength of not less than 80 N/mm2 after setting in 28 days of age without showing any segregation of ingredient materials and is adapted to be suitably used as high strength non-shrinkage grout mortar is also known (see Patent Document 6).    Patent Document 6: JP-A-2005-119885
Patent Document 6 describes “a mortar composition characterized by containing (A) cement, (B) granular cement clinker and (C) one or more materials selected from a water reducing agent, ultra fine powder and aggregate showing a specific gravity of not less than 2.7” (claim 1). It also describes using a calcium aluminoferrite based expansive additive (paragraph [0020]), a polycarboxylic acid based water reducing agent (paragraph [0014]) and silica fume as ultra fine powder (paragraph [0015]) but what is actually used is a naphthalene sulfonic acid based water reducing agent and a lime based expansive additive (paragraph [0024]). Moreover, it neither describe the silicon dioxide content ratio and the hydrogen ion concentration of the employed silica fume nor the use of calcium aluminoferrite based expansive additive, specific silica fume and polycarboxylic acid based water reducing agent in combination in order to obtain an excellent retention of fluidity, a high strength and a low shrinkage. As pointed out above, the invention described in Patent Document 4 avoids the use of an expansive additive and therefore those skilled in the art cannot easily get to the idea of using special siliceous fine powder described in Patent Document 4 as ultra fine powder as described in Patent Document 6 to be used with an expansive additive in combination.